A cobpoeation



Sept. 27,1921. Re.

RAILWAY. SIGNALLNQ v Original Filed Feb. 9, 1922 2 s t s t 1 INVENTORI v Q; 7" NW ATTORNEY Se t; 27 19 1.. 0. GRONDAHL 1 RAILWAY SIGNALING Orizinal Filed Feb. 9. 1922 2 Sheets-Sheet 2 lN-VENTCR BY Q;

6. ATTORNEY Reiaaued Sept. 27, 1927.

LABS O. GBONDAHL, OI' PITTSBURGH,

PENNSYLVANIA, ABSIGNOB are m UNION SWITCH & SIGNAL COMPANY, 01' SWISSVALE, PENNSYLVANIA, A CORPORATION OI PENNBYLVAN IA.

Original application fled Iebmry 8, 1822, Serial No. 1,588,711, dated September 14, 1986. Application M and is particularly well adapted to signaling of the type wherein roadsidesignals are govei'ned by track circuits which in turn are 7 characters controlled by thepassage of cars or trains along the track.

I will describe two forms of signaling apparatus embodying my invention and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view-showing one form of sig- 'naling apparatus embodying my invention while Fig. 2 is a view showin a modification of the apparatus shown in ig. 1 and also embodying my invention. Figs. 3, 4, 5, 6, 7 and 8 are views showing other forms =of apparatus whichmay be em 10 ed to control the stop lamp R,'all .of w 'c also embody my invention; 7

Similar reference characters refer to similar'parts ineachofthe several views.

Referrin' first to Fig. 1, the reference and F desi =of a-rnilway moves "in the direction indicated by the arrow- Th'ese 'rai laare divided into-a glurah ity of succe'ssiv'etrack, sections A-B etc., the isolation of the track sections bein accomplished, as here shown, b insulate j oints 2 in both of the lines of rai although any other suitable means 'of isolatln the sections may be em loyed without eparting from the spirit an scope of my invention.

Located adjacent the entrance end of each track section is a' railway si al, designated by the reference character with an expo- .nent corres ending to the location In the form here s own, each signal comprises three lamps G, Y and R, adapted whenlighted to indicate proceed caution and stop respectively. i

Each track section is. provided with a track circuit comprising a suitable source of current and a current receiving device, both of f which are connected across the track rails.

As here shown,;the source of ,current is the secondary 17 of a transformer designated bythe reference character T with an exponent corresponding to the location. The secondary is connected acrossthe. rails adjacent the exit end of the track section through a poleinvention relates to railway signaling,

ate the track rails. along which traific normally transformer D throu h through wire 20, grid mm; SIGNALING.

585,194. Renewed April 0, 1925. ori inal It. for reissue filed Augult 18, 18". lerill No.

instantaneous polarity of the current supplied to the rails, which pole-changing dewoe is hereinafter explained. The rimary 4 of each transformer T is connected with a transmission line 5, which is constantly supplied with alternating signaling current by a generator 6. The current receiving device n the form here shown, is a-transfo'rmer designated by the reference character D with an exponent corresponding to the location, the

pr ma of. which'is connected acrossthe rails a acent the entrance fendrof the track sect-ion.

I w Each signal is controlled in part two electron tubes E and E each comprisin a] vacuum bulb enclosing a The filaments 7 of t e two" filament '7, a 8, and-a plate 9.

bulbs at each signal location are constantly heated by the secondary 13 of the ad'acent' transformer T, through a circuit whic will tron tube E and E is provided with a grid circuit which is'energized from the secondary of the adjacent transformer D. Considering location B, for exam Ie, the gridcircuit for tube E is from t wire 18, grid and filament of tube E, an wire 19 to the secondary of transformer D Similarly, the grid circuit for tube E at this location is rom the seconda and filament of tube E and wire 19 to the secondary of transformer D 1 Each tube E and E is also provided with a plate circuit which is energized from the secondary 12 of the adjgcent transformer T. Considering location for exam Ie, the plate circuit for electron. tube E is in the left hand terminal of secondary 12, through the proceed lain tube E, heating ement 10 of a thermo-sensitive relay J, and heating element 10 of a thermo-sensitive relay J to the middlepoint of secondary 12; The plate circuit for tubeobvious from the drawing. Each else-- e secondary. of

changing device K for reversing the relative of transformer D,

G, plate and filament of It wi be observed that at anyg iven inbe positive with respect to the same instant that the grid 8 is stant the polarity of the grids 8 of the two tubes E and E are the same, whereas at any given instant the polarities of the plates 9 of tubes E and E are opposite. It follows that when the track circuit current is of one relative polarity, the plate 9 of tube E will filament at the positive with respect to the filament, so that the plate circuit. for tube E is conductive, whereas in tube E- the plate 9 will be negative with re: spect to the filament at the same instant that the grid is positive with respect to the filament I so that the plate circuit for this tube will be non-conductive; on'the other hand,

when the olarity of the track circuitcurrent- -is reverse. a the plate be non-conductive and the plate circuit for circuit for tube E will tube E will be conductive.

Each relay J and J comprises the heating element 10, and a thermo-sensitive element l'l-responsive to variations in temperaa. whole by the reference character K with ture b varying its electrical resistance. Each t ermo-sensitive element has a negative temperature coefiic-ient, and so it follows that when the heating element 10 is cold, that is, when it is not supplied with current, the resistance of' the thermo-sensitive element 11 iscomparatively high, whereas, when the heating element 10 is hot, that is, when it is supplied with current, the resistance-of the thermo-sensitive element 11 is comparativelv low,

The stop lamp of each signal is direct? connected 1 with a secondary 12 of the a thermo-sensitive element 11 of the adjacent relay J #7 When the relay J is energized, its resistance is so low that'lampR 1S extinuished, but when this relay is de-energized its resistance is so big? that suflicient current flows through lamp to cause this lamp to of the track-circuit current isesignated as an exponent corresponding to the location, and is in substance the same as. the apparatus disclosed in Fig. 2 of Letters Patent of the United States .No. 1,555,495 granted to Lars O. Grondahl and Lester E. Spray on l the 29th day of September, 1925, for electri' cal apparatus. Briefly described, this apparatus is as follows: The middle point of transformer secondary 17 is connectedwith .onetrack rail F by a wire 23, while the two outer terminals of this secondary areconnected with the other rail F through'wire 24: and the thermo-sensitive elements of two thermo-sen'sitiye relays J and J respectively, both. of which relays have negative temperature co-efiicients. The heating elementlO of relay J is'connected in a circuit which includes a secondary winding 16 on supplied by secondary 16.

jacent transformer T, and'this lamp is pro-. vided with a shunt which includes the .both lamps G and the adjacent transformer T and the secondary 22 of an ad'acent transformer H, these two secondaries eing so connected that they oppose each other. ofrelay J is connected with another secondary 22 on transformer H. The two primary windings 21 and 21 of transformer H are connected in series,-and are included in a circuit which contains a secondary adjacent transformer T and the. thermosensitive element The primary 21 and secondary 22 of trans-- former H are-inductively independent of the primary 21 and secondary '22. When relay J is energized, current of considerable value is supplied to transformer H 11 secondary 15, so that relay J is energize from secondary 22*. The voltage of secondar 22 substantially neutralizes that of secon arv 16, however, so that relay J is de-energized. The resistance of relay J is 15 on the.

by current- Ihe heating element 10 11 of the adjacent relay J ill) in the primaries of transformer H is low.

Relay J J a is energized due to current which is now The resistancefof relay J is, consequently, high, but the re sistance of relay J is low, so that current is supplied to the track rails by the left-hand half of secondary 17. It will be seen therefore, that current of one relative instantaneous polarity or the other is supplied to the track rails of each section according-as the thermo-sensitive relay J at the exit end of each section is energized or-de-energized.

e operation of the apparatus shown in 1, is as. follows: s here shown,- of location A is occupied by a car ortrain W, so

is then de-energized, whereas relay ill.

the track section to the left that the supply of current tothe primary of transformer D is discontinuedor reduced to an extremely low value, Both of the grid circuits at location A are conse-' quently de-energized, so

that both plate circuits are non-conductive,

with the'result that Y at .this location are extin'guished There being no current in either plate circuit, it and J the heating elements of which are common tothe plate circuits, are both deenergized. The sequently' high signal S is lighted.v The resistance of relay J is likewise high, so that in the pole-changing device K relay J is energized and follows that the relays J resistance of relay J is-conso that the stop lamp R of relay J is de-energized,- with the result that I the track section A-B is supplied with eurrent from the left-hand half of transformer.

secondary 17. The relative polarity of this current is such that the electron tube E at 1s energized by the current plate circuit of tube E. Relay J at location B is also energized, so that in the polechan ing apparatus K? the relay J isenergize and the relay J is de-energized. This causes current from the right-hand halfof secondary 17 of transformer T to be supplied to the track circuit for section 13-0,

. such as to render thetube E at location 0 series directly the stop lamp R is connected across a trans Wh multiple with "such. that when relay J stop lamp. are. illustrated an additional relay 10 of which isalso connected across secondary 14. A resistance 4 cluded in the circuit as J is energized, the amount of current flowconductive and the is consequently illuminate relays J former secondary 14, and that the sensitive element'of relay J is connected in' b the lamp, the control being b the preceding views,

and the relative polarity of this current is tube E tion non-"conductive. Lam

at this same locaand lamp Y is extinguished, lamp R also being extinguished because relay J is energized by the current in the plate circuit for tube E.

Referring now to Fig. 2, the apparatus shown in this view is the same as that shown in Fig. 1, except that the thermo-sensitiv'e and J 2 are removed from the common return wire for the plate circuit; of electroirtubes E and E and are placed in across the secondary of the ad acent transformer D. It follows that each pair of relays J gized when thecorresponding track section is unoccupied, j16.nd de energiz'ed when such track section is'ioc'cupied, so that these relas are energized and de-energized under t a same cond1t1ons as in Fig.1.

The operation of. the system shown in Fig. 2 W111 be-readily understood in view of the detailed explanation set forth herein before ofltheoperation of the system shown in Fi" 1. I Iniigs. 1 and 2, it will be :observed that thermois de-energized the lamp is lighted, but that when this relay is energized suflicien-t current is shunted away from .the lamp to extinguish the lam Other arrangements for thecontrol of the in Figs. 3, 4, 5, 6.,

7 and 8. a Referring to Fig. 3, the. lamp R and the thermo-sensitive element of relay J are connectedin multiple across secondary 14 as in but in series with the lamp .is the thermo-sensitive element 11 of J. the beatingelement is preferably in shown. 'When relay ing in the heating element of relay J is so small that this relay-is also ile-energized,

' plea An additional G of signal S it balances the voltage of and J. will be eneradditional thermo-sensitive rela and 2 in that the load on relay J "is reduced shown in Figs. 1

and a smaller change in voltage at this relay lishes the desired result. ig. 4 the apparatus for the control of lamp R embodies the potentiometer princisecondary 26 on transaccom In former T is connected across a resistance 27,

the thermo-sensitive element of rela J be: ing included in such connection, w ile the circuit for secondary-14 includes the lamp R and a portion of resistance 27. When relay J is energized, the drop acro.:s the ortion of resistance 27 which is in series wit lamp secondary 14 so that the lamp is extinguished. When relay J becomes e-energized, the current in resistance 27 is reduced, so that the voltage acro's the left-hand portion is reduced and no longer balances the voltage of secondary 14; lamp R then becomes lighted.

Fig. 5 is the J 5 is introduced for thesame reason as in Fig. 3-, so that the control of 1am R may be efflected bya :maller change in the voltage acrossthe left-hand portion of resistance 27.

oi-this resistance same as Fig. 4 except thatan 30- and the thermo-sensitive element of relay J while the brid en relay J balanced so that ut when relay J 'ge member is the lamp R.

become} de-energized the then supplied to lamp R to light this lamp. heap aratus showniin Fig. 7 is the same as that. o 6 except that a step-up transformer -31is introduced between the bridge and the lamp R toincrease thevoltage apalanced.

The apparatus shown bodies the Wheatstone bridge principle, but dillers from Fig. 6 in thatthe lamp is controlled by two .relays J and J the thermosensitive elements of which constitute two.

lamp R, and; resistance 32 to secondary 14,

is energized the bridge is current flows in lamp. R,

alance is destroyed and suflicient current is.

plied to the lamp when the bridge is un-" in Fig. 8 also emished. When the reappended claims without departing sections, two electron tubes, a

and so the lamp will become lighted. If desired, a transformer may be interposed between the bridge and the lamp as in Fig. 7.

Althou h I have herein shown and described on y certain forms of signaling up aratus embodying In invention, it is un er-- stood that various 0 an es and modifications may be made therein within the scope of the rom the splrit and scope of my invention.

Having thus described my invention, what I claim is: I

1. In combination, a section of railway track, a source of alternating current re versibly connected with the rails of said rid circuit for each tube ener 'zed from sai track rails in such manner t at the grids have the same polarity at any. given instant,'a transformer the primary of which is constantly supplied with current of the same frequency as that supplied to said track rails, a plate circuit for each tube one of which extends from the middle point of the secondary. of said transformer to one secondary terminal and the other of which extends from the said middle point to the other secondary terminal, a proceed signal and a caution signal controlled by saidtwo late circuits respectively, a device includ in circuit with said secondary and common to said'two plate circuits and responsive to variations -m the current strength therein, and a stop signal controlled by said device.' i

r 2,111 combination, a section of railway track, a source of alternating current reversibl'y connected-with the rails of said section,- twoelectron' tubes, a grid circuit for each tube ener 'zed from said track rails in such manner t at the grids havethe same polarity at any given instant, a transformerthe primary of which is constantly supplied witly current of the same frequency as that supplied to said track rails, a late circuit for each tube one of which exten s fron'i'the middle point of the'seconda v of said transformer to one secondary terminal and the other of which extends from-the said middle point to the other secondary terminal, a roceed sig-- na'l and a. caution signal contro ledby said 7 template circuits respectivel a relay comprising a heatin element inc uded in circuit with said secon ary and common to the two plate elrcuits'and' a member:.of -thermo-'sensitive substance, and a stop signalcontrolled two 5 by said substance; H

I 3. combination, a;." sectionof railwayj track, area of alternatingcurre t revere-,

ibly withth'e rails of-said-section, two electron tubes, a grid-circuit for-each from saidtrackrails, two

mg a conductor common'tofthe two, the cir cu tsifor said tubes being sqscqnnected that one plate circuit or the other conductive 1- accordin as the current supplied to the track re s' is of one instantaneous relative polarity or the other, a roceed signal and a caution signal controlled by said two plate circuits respectively, a device controlled by versibly connected with the rails of said section, two electron tubes, a grid circuit for each tube energized from said track rails, two latecircuits one for each tube and ineluding a conductor common to the two, the circuits for said tubes being so connected that with track current of one relative po larity the grid and plate otone tube are positive at the same instant andt-he grid and plate of the other tube are positive and negative at the same instant, while with track current of the other relative polarity the grid and plateof the first tube are positive and negative at the same instant and the grid and plate of the-second tube are both positive at the sanle' instant, 'a device controlled by the conductor common to the two plate circuitsiand responsive to current amplitude'variations therein, and signaling and by said device.

versibly" connected tion, two electron t hes, a grld circuit for each tube energized from said track rails, two

glternating current rethe circuits for said tubes being so connecte that one plate circuit or the other is con ductive accordin as the current --supphed tothe track rai s is of one instantaneous plitude variations therei n,-. and, .signaling. means governed by. said and b said device. i U

,6. Iii combination, a section of railway track," asourceofalternatin current reversibly connected with the m1 3 ofsaid section,"two electron tubesila. grid circuittor each ,tube energizedzfroin said track rails,

inclu a conductor common to the two the circults for. said tubes being so connected that one plate circuit or thepother,ifs conductive accordin' as the current supplied to the track .rai s isjof one instantaneous relative larityor the other, a heating elementinc uded insaidconductor common to the twoplate circilits, athermo-sensitive ele mentsubjectedto variations -in the temperau o a d heating ;,-e. m t d a m section of railway track, a source of alternatin current re' 5. In' combinationg a section of railway track, a source of w'th the rails of said sec late circuitsvone for each tube and mclu n a conductor common to the twoi' two plate circuits circu1ts, one for each tube and I nected that one plate circuit or means controlled by said two late circuits and b said thermo-sensitive e ement 7. n combination, a section of railway track, a source of alternating current reversibly connected with the rails of said section, two electron tubes, a grid circuit for each tube energized from said track rails, two plate circuits one for each tube and including a conductor common to the two, the circuits for said tubes bein so cone other is conductive according as the current supplied to the track rails is of one instant-a neous relative polarityor the other, a relay comprising a thermo-sensitive element and a heating element included in said common conductor a proceed lamp and a caution lamp included respectively in said two plate circuits, :1 stop lamp connected with a. source of current, and a shunt around said stop lamp including the thermo-sensitive element of said relay. v

8. In combination, a section of railway track, a. source of alternating current reversibly connected with the rails of said section two electron tubes, a rid circuit for eac 7 tube energized from sai track rails, two plate circuits one for each tube, the circuits for said tubes being so connected that one plate circuit or the other is conductive according as the current supplied to said track rails is of one relative polarity or the other, a'proceed and a caution signal controlled by said two plate circuits respectively, and a stop signal responsive "to the presence and absence of vvehicles in said track section.

In testimony whereof I aflix my signature.

LABS o. GRONDAHL. 

